1. Field of the Invention
The present invention relates to a battery-powered drill including a housing, a handle connected with the housing, an electrical drive motor located in the housing, a battery unit insertable into the housing and fixedly securable therein for supplying electrical power to the electrical drive motor, a connection device for connecting the battery unit with the electrical drive motor and including a connector element projecting from the battery unit and a mating connector element provided in the housing and electrically connectable with the connector element provided on the battery unit upon mounting of the battery unit in the housing.
2. Description of the Prior Art
German Publication DE-195 21 423 discloses a battery-powered drill having an electrical drive motor to which the electrical power is supplied from a battery unit which is mounted on the drill housing. The battery unit is fixedly secured to the drill housing by a pin-shaped locking element which is arranged on the housing and is spring-biased into an opening formed in the battery unit. The pin-shaped locking element is pulled out of the opening in the battery unit with a coupler. The electrical connection between the drive motor and the battery unit is insured by a connector element which is provided on the battery unit and, upon mounting of the battery unit on the housing, is connected with a mating connector element provided on the housing.
To insure a reliable engagement of the locking element in the opening formed in the battery unit, the cross-section of the opening is made larger than the cross-section of the locking element. The clearance, which is formed between the locking element and the opening, leads to a relative displacement between the battery unit and the housing and, thus, between the cooperating connector elements when the drill is subjected to shocks. The relative movement between the connector elements may damage the contact elements of one or both connector elements which, in turn, may result in a faulty contact therebetween.
Accordingly, an object of the present invention is to provide a battery-powered drill that would insure a reliable, fixed mounting of the battery unit on the drill housing so that no relative movement between the connector elements of the battery unit and the housing takes place when the drill is subjected to shocks.
This and other objects of the present invention, which will become apparent hereinafter, are achieved, according to the present invention, by providing press pin means which supports the battery unit against the housing and which is displaceable against a spring-biasing force upon mounting the battery unit on the housing, securing fixedly the battery unit on the housing.
The spring for biasing the press pin means becomes preloaded upon the mounting of the battery unit on the housing, and applies to the housing, in the locking position of the battery unit on the housing in which the connector elements are connected with each other, a force acting in the direction opposite to the mounting direct of the battery unit. As a result of the application of the spring force to the housing, a locking element or member which is provided on the battery unit and projects into an opening formed in the housing, is pressed against an inner profile of the opening facing in the mounting direction. In this way, the clearance between the opening and the locking member is eliminated which prevents the relative movement between the two connector elements when the drill is subjected to shocks.
For manufacturing reasons, preferably, the press pin element is provided on the battery unit and is displaced against a biasing force in a direction opposite to the mounting direction. For receiving the press pin element and the biasing spring, bore(s) is (are) provided in the battery unit. The receiving bore is open in the mounting direction and is closed in the opposite direction.
In order to provide for mounting of the battery unit on the drill housing and insure that the battery unit remains in the mounting position, without the press pin element of the battery unit being pressed out of the receiving bore and, thus, without the interruption of the contact between the connector elements, advantageously, the press pin element cooperates with a mating surface provided in the housing and facing in the direction opposite the mounting direction.
For manufacturing reasons, advantageously, the mating surface provided in the housing is formed by a bolt connected with the housing and arranged coaxially with the press pin element. At that, the outer diameter of the bolt is smaller than the outer diameter of the press pin element. Due to its smaller diameter, the bolt can project into the bore, in which the press pin element is received, when the battery unit occupies its final position on the drill housing.
The novel features of the present invention, which are considered as characteristic for the invention, are set forth in the appended claims. The invention itself, however, both as to its construction and its mode of operation, together with additional advantages and objects thereof, will be best understood from the following detailed description of preferred embodiment, when read with reference to the accompanying drawings.